All three are fluoropolymers, all three resist heat and chemicals far better than PVC or rubber, and all three show up on the same datasheets - which is exactly why they get confused. The real differences come down to how each resin is processed and what that means for temperature ceiling, wall-thickness precision, and cost.
FEP - the balanced, cost-effective choice
FEP is melt-processible, meaning it can be extruded onto a conductor the same way ordinary plastics are. That gives it a smooth, consistent wall thickness and a clean surface finish at a lower cost than PTFE. It handles sustained industrial operating temperatures comfortably, resists oils and moisture well, and is the insulation we reach for most often on OEM harness and general industrial wiring where cost, precision and heat resistance all matter together. See the full ratings on our FEP insulated wires page.
- Melt-extruded - tighter tolerances, smoother finish
- Strong chemical and moisture resistance
- Best value of the three fluoropolymers
- Good fit for harness, automation and control wiring
PFA - FEP's precision with a higher heat ceiling
PFA is also melt-processible, so it extrudes with the same dimensional precision as FEP, but its molecular structure lets it hold up at higher continuous temperatures. That makes it the choice when a design needs PTFE-level thermal performance without giving up tight tolerances - our PFA insulated wires and PFA RTD cables are typically specified where an FEP-rated wire is close to its ceiling but the application still needs precise, thin-wall construction.
- Higher continuous operating temperature than FEP
- Extrudable, so tolerances stay tight even at thin wall thickness
- Excellent chemical resistance, suited to RTD and sensor cabling
- Costs more than FEP, less design compromise than PTFE
PTFE - the highest temperature ceiling
PTFE cannot be melt-extruded; it is paste-extruded and sintered, which is a slower, more demanding process. In exchange, it tolerates the highest continuous temperatures of the three and keeps its properties across the widest range of aggressive chemicals. Our extruded Teflon wires and Teflon wires use PTFE where an application genuinely needs that ceiling - heating elements, aerospace harnesses, and equipment operating right at the edge of what FEP or PFA can take.
- Highest continuous temperature rating of the three
- Outstanding resistance to solvents and aggressive chemicals
- Harder to hold tight wall-thickness tolerances than FEP/PFA
- Best reserved for applications that actually need the extra headroom
How to decide
In practice, the decision usually comes down to three questions:
- What's the real continuous operating temperature? Not the peak, the sustained one. If FEP covers it with margin, there's rarely a reason to pay more for PFA or PTFE.
- Does the application need tight OD tolerance or thin wall construction? If so, lean FEP or PFA over PTFE.
- What chemicals or solvents will the wire actually contact? All three fluoropolymers resist most oils and moisture well; PTFE has the edge against the most aggressive solvents.
If you're unsure which of these fits your drawing, send us your voltage, temperature and environment requirements and our team will recommend a construction from our cable catalogue rather than leave you to guess.
Frequently Asked Questions
What is the main difference between FEP, PFA and PTFE?
FEP and PFA are melt-processible fluoropolymers that can be extruded with tight tolerances, while PTFE is paste-extruded and sintered. PTFE handles the highest continuous temperatures, PFA sits close behind it with better manufacturing precision, and FEP offers the best balance of cost, precision and heat resistance.
Is PFA better than FEP?
PFA tolerates higher continuous temperatures than FEP while keeping similar manufacturing precision, but it costs more. FEP is the better choice when its temperature rating already covers the application, since it offers the same tight tolerances at a lower price.
When should I choose PTFE insulated wire over FEP or PFA?
Choose PTFE when the application needs the highest possible continuous temperature rating or exposure to the most aggressive chemicals, and when tight OD tolerance is not the primary constraint.
